How can I differentiate between C. difficile infection and other causes of antibiotic-associated diarrhea in my patients?

To differentiate Clostridioides difficile infection (CDI) from other causes of antibiotic-associated diarrhea, start with a thorough clinical assessment focusing on symptom severity, history, and risk factors. CDI typically presents with watery diarrhea, abdominal pain, and sometimes fever, often following antibiotic use, but these symptoms can overlap with other causes of antibiotic-associated diarrhea ¹.

Testing stool samples for C. difficile toxins is essential; a positive toxin test supports CDI diagnosis, but a negative test does not completely exclude it if clinical suspicion remains high, warranting repeat testing ¹. Colonization without infection is common, so clinical correlation is crucial to avoid false positives ¹.

Other causes of antibiotic-associated diarrhea include non-infectious etiologies such as direct antibiotic effects on gut flora or other infections; these usually lack the systemic features and severity seen in CDI ¹. In cases where CDI is suspected but toxin tests are negative, consider specialist advice and retesting ¹.

Assess severity: severe CDI often requires hospital admission and specialist input, while mild cases may be managed in the community with cessation of the offending antibiotic if appropriate ¹. Avoid antimotility agents as they can worsen CDI ¹.

Additional clinical clues include the presence of risk factors such as recent hospitalization, advanced age, immunosuppression, or prior CDI episodes, which increase the likelihood of CDI over other causes ¹. Hygiene measures and infection control are important to prevent spread, as C. difficile spores are resistant to alcohol hand rubs and persist in the environment ¹.

In summary, differentiation relies on clinical assessment, stool toxin testing with awareness of its limitations, consideration of risk factors, and exclusion of other causes by history and examination. Prompt specialist advice is recommended if CDI is suspected but not confirmed or if symptoms are severe ¹. This approach aligns with established UK guidelines and is supported by clinical literature emphasizing the importance of clinical judgment alongside laboratory testing (Bartlett and Gerding, 2008).